This invention relates to high-throughput infrared spectrometers and high-throughput infrared spectroscopic methods.
Single-beam infrared spectrometric measurements can be vulnerable to the infrared signature of water vapor and other variations. For this reason, infrared spectrometers are generally calibrated before each set of measurements. This can require purging the instrument, recording a reference spectrum, reopening the instrument, and again purging the instrument with a sample in place, before actual measurements can be taken from the sample.
Several aspects of the invention are presented in this application. These relate to improvements including improvements to spectrometers and other optical instruments, improvements to vessels for spectrometers, and related methods.
In one general aspect. the invention features a spectrometer that includes an infrared source, a spectrally selective element, and a cell array. The cell array includes walls that define a number of cavities. The spectrometer also includes an infrared spatial detector responsive to infrared radiation travelling from the infrared source through contents of at least two of the cavities as well as through the spectrally selective element.
In preferred embodiments, the spatial infrared detector can be an imaging detector. The imaging detector can be an imaging array implemented using semiconductor manufacturing techniques. A first of the walls can be made of a first material, with a second of the walls being made of second material, and with the first and second materials having significantly different infrared spectral properties. There can be a gasket between the first and second of the walls. The cell array can include at least one infrared-transparent wall. The cell array can include at least one reflective surface. The source and detector can be arranged relative to the reflective surface of the cell array such that infrared radiation is reflected from the source to the detector without passing through any of the walls. The array can be made up of separate vessels. There can be a cover for covering at least one of the cells, or even all of the cells. There can be a gasket between the cover and at least the walls defining one of the cells. At least one of the cells can include a reference substance. A plurality of the cells can be covered by the cover and with the plurality of cells each including a different reference substance. The sample vessel can be a one-piece element with the cells in rigid relationship with each other. At least one of the cells can include a reference substance. A plurality of the cells can each include a different reference substance. The spectrometer can include a purging mechanism for purging a space between at least two of the infrared source, the cell array, and the spatial infrared detector. An actuator can move the cell array. At least one of the cells can include a feed opening. The cells can form part of a process stream conduit.
In another general aspect, the invention features a sample vessel for a spectrometer that includes walls defining a number of cells with at least a first of the walls is being infrared-transparent wall having a first infrared spectral response. In preferred embodiments, a second wall can have a second infrared spectral response different from the first spectral response. At least one of the cells can include a reference substance. The sample vessel can be a one-piece element. At least one of the cells can include a feed opening. The cells can form part of a process stream conduit.
In a further general aspect, the invention features a sample vessel for a spectrometer that includes walls defining a number of cells and at least one reflecting surface located at one or more of the walls and having at least one optical axis crossing the cells. In preferred embodiments, at least one of the cells can include a reference substance. The reflecting element can be deposited on a bottom wall of at least one of the cells in the cell array. The reflecting element can be deposited on a top surface of a bottom wall of at least one of the cells in the cell array. The reflective surface can be made of aluminum. The sample vessel can be a one-piece element The walls can be made of a material having a significant infrared spectrum.
In another general aspect, the invention features an infrared spectrometer that includes a plurality of means for holding substances while being simultaneously located in the spectrometer, means for shining infrared light such that it interacts with the substances held by the plurality of means for holding, means for detecting at least a portion of the infrared light after it has interacted with contents of the means for holding substances, and means for deriving relative spectral information based on signals derived from the plurality of cells detected in the step of detecting. In preferred embodiments, the means for deriving spectral information can include means for capturing an infrared image. The means for shining can be for simultaneously shining infrared light through all of the means for holding, with the means for detecting being for simultaneously detecting infrared light from all of the means for holding. The spectrometer can include means for purging the means for holding before the step of detecting. At least one of the means for holding can include a reference means. The means for deriving can be for determining whether an infrared spectrum of a sample substance in a first of the means for holding is closer to an infrared spectrum of a reference substance in a second of the means for holding or to an infrared spectrum of a reference substance in a third of the means for holding.
In a further general aspect, the invention features an infrared spectroscopy method that includes shining infrared light toward contents of a plurality of cells simultaneously located in an instrument, detecting at least a portion of the infrared light after it has interacted with contents of the cells, and deriving relative spectral information based on signals derived from the plurality of cells detected in the step of detecting. In preferred embodiments, the step of detecting can act on infrared light that has interacted with the plurality of cells by capturing an infrared image. The step of shining can simultaneously shine infrared light through all of the cells and with the step of detecting simultaneously detecting infrared light from all of the cells. A first of the cells can contain a reference substance, with a second of the cells containing a sample substance, and the step of deriving comparing spectral signals from the reference substance and the sample substance. The method can include the step of purging the cells before the step of detecting. The method can include further steps of detecting and deriving for different sample substances in one of the cells and the same reference substance in another of the cells. The method can include further steps of detecting and deriving for different sample substances in one of the cells and a same plurality of different reference substance in others of the cells. One of the cells can include a sample substance and at least a first and a second of the cells can include different reference substances, with the step of deriving determining whether an infrared spectrum of the sample substance is closer to an infrared spectrum of the reference substance in the first cell or to an infrared spectrum of the reference substance in the second cell. One of the cells can include a sample substance and at least a first and second of the cells that include different reference substances, with the step of deriving determining a measure of relative quantities in the sample substance of the reference substance in the first cell and the reference substance in the second cell. The sample can include a product or an intermediate from a reaction and the first and second reference substances can be reagents or intermediates for the reaction. The step of determining can include performing a multivariate spectral analysis. The method can further include changing a process in response to result of the step of determining.
In another general aspect, the invention features a spectrometer that includes a cell array including walls defining a number of cavities, a number of reference samples, each in one of the cavities of the cell array, and a spatial detector responsive to radiation travelling from the infrared source through contents of a plurality of the cavities. In preferred embodiments, the cavities of the cell array that include the reference samples can be sealed, with the spectrometer also including an unsealed cavity for a sample. A processor can be operative to compare spectral information from the number of cavities with spectral information from a sample in a sample cavity.
In a further general aspect, the invention features an optical process monitoring instrument that includes a plurality of process feed conduits, a spatial detector responsive to the feed conduits, and a signal processor responsive to the spatial detector. In preferred embodiments, at least a first of the conduits can be operatively connected to at least a second of the conduits so that contents of the first and second conduits can react.
In another general aspect, the invention features an infrared spectroscopy method that includes shining infrared light toward a plurality of substrate areas simultaneously located in an instrument, detecting at least a portion of the infrared light after it has interacted with substances located on the substrate areas, and deriving relative spectral information based on signals derived from the substances detected in the step of detecting. In preferred embodiments, a first of the areas can support a reference substance, with a second of the areas containing a sample substance, and the step of deriving can compare spectral signals from the reference substance and the sample substance. The method can further include the step of purging a volume between the substrate and apparatus used to perform the step of detecting. One of the plurality of areas can include a sample substance and at least a first and a second of the areas that include different reference substances, and wherein the step of deriving determines whether an infrared spectrum of the sample substance is closer to an infrared spectrum of the reference substance on the first area or to an infrared spectrum of the reference substance on the second area. The step of determining can include performing a multivariate spectral analysis. The method can include a step of initiating a reaction between at least one reagent and the substances on the different areas.
Systems according to the invention can be advantageous in that they can improve the throughput of infrared spectrometers. By providing simultaneous capture of spectra from a library of reference samples at the same time as measurements are taken, spectrometers according to the invention can perform detailed comparisons between a sample and those reference samples in a single acquisition cycle. And by providing a number of sample vessels, a number of measurements can be taken either simultaneously, or in close succession. Such improvements can translate into throughput gains that permit high numbers of samples to be analyzed either in discrete batches or as part of a continuous process.